DeJaccke
New Member
The Intro
So, I had heard of this dinky little switch idea for locking up the torque converter clutch in auto transmissions. The idea being that with no slip you should get much better fuel economy, much less heat and better control over what the transmission is doing. Especially in a car that likes to hunt for gears when you hit hills on the highway.
For Reference of this article I drive a 1993 WD21 Terrano Widebody with a TD27 Turbo Diesel Engine and an RE4R01A Transmission.
I also should apologize I forgot to take photos until the last moment so my pics are of the switch and wiring in place with paneling back on.
EDIT: My vehicle has a Power/Auto/Hold Switch in the console for the electronic controlled transmission. When I am using this mod I leave this switch in HOLD mode to avoid the transmission trying to give me more power by dropping back suddenly. Caution should be exercised if you have a transmission without this switch to not allow it to constantly kick down gears as this could put excessive shock on components that are designed to work with a slippery box. Using the O/D button to choose a lower gear without hard acceleration is a good way to manage this shock when climbing long/steep hills.
This should not be used for hard acceleration or around town as the rest of the components in the transmission aren't designed to cope with the hard shifting under power! The best use of this is for highway use or when towing.
After looking into it I found a number of companies selling switch setups for $140 odd and all that was really involved in the most complex setups was applying 12v manually to the lock-up solenoid, the same I could achieve with:
A switch (To engage/disengage the lock)
A globe (or something else to cause resistance and trick the TCU into thinking nothing was wrong with the solenoid)
A rectifier diode (to prevent feeding 12v back into the Transmission Control Unit)
And some wire and terminals.(To hook into the 12v line to the Solenoid and a supply).
Most Importantly a factory manual to know which wire to splice to...
I got mine from Here
Everything else was bought off the shelf from Jaycar for under $15. Try a Solar place for the Rectifier Diode should be cheap but no-one had any when I dropped in.
The Plan and Execution
I then sat down and drew up a diagram like this:
And went and got the bits... Rectifier diodes capable of dealing with even this little current were in short supply around town so I decided to just ensure with a decent 2 position missile switch that there was no feedback on the line to the Transmission Control Unit. The other issue was do I really Want/Need a light going off every time the TCU decides it wants to lock the torque converter while I have it's circuit disconnected? After some deliberation and some more research I found that there was no need, all I would cause is the TCU reporting an error with the Lockup Solenoid.
So I decided to take the shortcuts...
Wiring up the switch and cable was easy then I had to find where I could splice into the TCU-Solenoid line and pull reliable power for the manual control. I had seen some people splice store bought systems in under the bonnet where the solenoid line joins the main loom (the Blue wire):
But being one of those who doesn't like a million wires under the bonnet I figured the loom would have to run through the cab somewhere to get to the TCU in the rear quarter panel.
-Note the Green Wire with Yellow Stripe! there are a few so look at what other colours are in the same loom and before Cutting, scrape the wire lightly and do a continuity check back to the blue wire in the above photo to make sure you're not hooking power to the wrong Wire!
I found it under the kick panel, mounted the switch, connected into the line then ran a power line to the back of the lighter socket (I only ever use my Lighter socket for charging phones [under 3 Amps on a 20A fused line]) with a dedicated 10A fuse to ensure it will separate in the event something goes wrong.
The Verdict...
This mod has got to be the best bang for buck mod I have ever done.
The car shifts harder and more predictably than before and doesn't wander through gears when on the highway.
Fuel economy is massively improved. I would guess I would get at least 800Km to an 80l Tank now on the open road.(100Km+ Improvement)
And I can maintain speed much better up inclines without revving theBejeezus out of the engine.
-----Notes for people Trying This!-----
-Make sure your switch will not ground on anything even when vibration is at a peak!! I wouldn't want to lose my Transmission Computer when out in the middle of nowhere and I'm sure you don't either.
-Make sure you are wiring up the Switch so that the switch cover is OPEN when the TC is LOCKED to ensure you can easily check/toggle when traffic stops dead in front of you.
-When starting your car and the PWR light on the Tranny Toggle switch is flashing to tell you there is a lock-up solenoid problem it probably just means you used the solenoid manually last time you were driving and didn't put a resistor in to fool the TCU. But to be sure check the manual there is a transmission self check diagnostic in there!
-Turn the switch off before coming to a stop! The RE4R01A Tranny doesn't lock in 1st so you won't spit the tranny or stall the engine but I don't want to know what damage it could do if you allowed it to down-change to 1st every time with the way mine behaved (Shuddering until it realized it should shift) the first time I forgot to disengage before stopping.
-Finally! ENJOY!!! This is the first complete set of instructions I've seen on the internet for doing this DIY so hopefully it'll help out lots of people! I think it should work for most Elec Transmissions just the wires to connect to will change!
EDIT: When writing this I am expecting that anyone who does a DIY mod, especially affecting the drive-train of the vehicle, understands that the mod may compromise some reliability in the operation of the components affected by the MOD. I have seen very few bad outcomes from doing this particular mod but if there is already some damage to the transmission or weakness in the drivetrain I would not be expecting that this mod would help with these problems. However if your drive-train is stronger than it needs to be and your transmission comes out in a car with a heavier body and more powerful engine how can a little more shock compromise a perfectly healthy transmission in your lighter, less powerful vehicle... Especially if you use it for it's intended purpose with the caution due to any aftermarket drive-train Mod. (eg. Increasing boost and diesel flow will inevitably lead to an earlier rebuild being required.)
So, I had heard of this dinky little switch idea for locking up the torque converter clutch in auto transmissions. The idea being that with no slip you should get much better fuel economy, much less heat and better control over what the transmission is doing. Especially in a car that likes to hunt for gears when you hit hills on the highway.
For Reference of this article I drive a 1993 WD21 Terrano Widebody with a TD27 Turbo Diesel Engine and an RE4R01A Transmission.
I also should apologize I forgot to take photos until the last moment so my pics are of the switch and wiring in place with paneling back on.
EDIT: My vehicle has a Power/Auto/Hold Switch in the console for the electronic controlled transmission. When I am using this mod I leave this switch in HOLD mode to avoid the transmission trying to give me more power by dropping back suddenly. Caution should be exercised if you have a transmission without this switch to not allow it to constantly kick down gears as this could put excessive shock on components that are designed to work with a slippery box. Using the O/D button to choose a lower gear without hard acceleration is a good way to manage this shock when climbing long/steep hills.
This should not be used for hard acceleration or around town as the rest of the components in the transmission aren't designed to cope with the hard shifting under power! The best use of this is for highway use or when towing.
After looking into it I found a number of companies selling switch setups for $140 odd and all that was really involved in the most complex setups was applying 12v manually to the lock-up solenoid, the same I could achieve with:
A switch (To engage/disengage the lock)
A globe (or something else to cause resistance and trick the TCU into thinking nothing was wrong with the solenoid)
A rectifier diode (to prevent feeding 12v back into the Transmission Control Unit)
And some wire and terminals.(To hook into the 12v line to the Solenoid and a supply).
Most Importantly a factory manual to know which wire to splice to...
I got mine from Here
Everything else was bought off the shelf from Jaycar for under $15. Try a Solar place for the Rectifier Diode should be cheap but no-one had any when I dropped in.
The Plan and Execution
I then sat down and drew up a diagram like this:
And went and got the bits... Rectifier diodes capable of dealing with even this little current were in short supply around town so I decided to just ensure with a decent 2 position missile switch that there was no feedback on the line to the Transmission Control Unit. The other issue was do I really Want/Need a light going off every time the TCU decides it wants to lock the torque converter while I have it's circuit disconnected? After some deliberation and some more research I found that there was no need, all I would cause is the TCU reporting an error with the Lockup Solenoid.
So I decided to take the shortcuts...
Wiring up the switch and cable was easy then I had to find where I could splice into the TCU-Solenoid line and pull reliable power for the manual control. I had seen some people splice store bought systems in under the bonnet where the solenoid line joins the main loom (the Blue wire):
But being one of those who doesn't like a million wires under the bonnet I figured the loom would have to run through the cab somewhere to get to the TCU in the rear quarter panel.
-Note the Green Wire with Yellow Stripe! there are a few so look at what other colours are in the same loom and before Cutting, scrape the wire lightly and do a continuity check back to the blue wire in the above photo to make sure you're not hooking power to the wrong Wire!
I found it under the kick panel, mounted the switch, connected into the line then ran a power line to the back of the lighter socket (I only ever use my Lighter socket for charging phones [under 3 Amps on a 20A fused line]) with a dedicated 10A fuse to ensure it will separate in the event something goes wrong.
The Verdict... This mod has got to be the best bang for buck mod I have ever done.
The car shifts harder and more predictably than before and doesn't wander through gears when on the highway.
Fuel economy is massively improved. I would guess I would get at least 800Km to an 80l Tank now on the open road.(100Km+ Improvement)
And I can maintain speed much better up inclines without revving the
Bejeezus out of the engine.-----Notes for people Trying This!-----
-Make sure your switch will not ground on anything even when vibration is at a peak!! I wouldn't want to lose my Transmission Computer when out in the middle of nowhere and I'm sure you don't either.
-Make sure you are wiring up the Switch so that the switch cover is OPEN when the TC is LOCKED to ensure you can easily check/toggle when traffic stops dead in front of you.
-When starting your car and the PWR light on the Tranny Toggle switch is flashing to tell you there is a lock-up solenoid problem it probably just means you used the solenoid manually last time you were driving and didn't put a resistor in to fool the TCU. But to be sure check the manual there is a transmission self check diagnostic in there!
-Turn the switch off before coming to a stop! The RE4R01A Tranny doesn't lock in 1st so you won't spit the tranny or stall the engine but I don't want to know what damage it could do if you allowed it to down-change to 1st every time with the way mine behaved (Shuddering until it realized it should shift) the first time I forgot to disengage before stopping.
-Finally! ENJOY!!! This is the first complete set of instructions I've seen on the internet for doing this DIY so hopefully it'll help out lots of people! I think it should work for most Elec Transmissions just the wires to connect to will change!
EDIT: When writing this I am expecting that anyone who does a DIY mod, especially affecting the drive-train of the vehicle, understands that the mod may compromise some reliability in the operation of the components affected by the MOD. I have seen very few bad outcomes from doing this particular mod but if there is already some damage to the transmission or weakness in the drivetrain I would not be expecting that this mod would help with these problems. However if your drive-train is stronger than it needs to be and your transmission comes out in a car with a heavier body and more powerful engine how can a little more shock compromise a perfectly healthy transmission in your lighter, less powerful vehicle... Especially if you use it for it's intended purpose with the caution due to any aftermarket drive-train Mod. (eg. Increasing boost and diesel flow will inevitably lead to an earlier rebuild being required.)
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